kernel/sysctl_binary.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/stat.h>
   3 #include <linux/sysctl.h>
   4 #include "../fs/xfs/xfs_sysctl.h"
   5 #include <linux/sunrpc/debug.h>
   6 #include <linux/string.h>
   7 #include <linux/syscalls.h>
   8 #include <linux/namei.h>
   9 #include <linux/mount.h>
  10 #include <linux/fs.h>
  11 #include <linux/nsproxy.h>
  12 #include <linux/pid_namespace.h>
  13 #include <linux/file.h>
  14 #include <linux/ctype.h>
  15 #include <linux/netdevice.h>
  16 #include <linux/kernel.h>
  17 #include <linux/uuid.h>
  18 #include <linux/slab.h>
  19 #include <linux/compat.h>
  20
  21 static ssize_t binary_sysctl(const int *name, int nlen,
  22         void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
  23 {
  24         return -ENOSYS;
  25 }
  26
  27 static void deprecated_sysctl_warning(const int *name, int nlen)
  28 {
  29         int i;
  30
  31         /*
  32          * CTL_KERN/KERN_VERSION is used by older glibc and cannot
  33          * ever go away.
  34          */
  35         if (nlen >= 2 && name[0] == CTL_KERN && name[1] == KERN_VERSION)
  36                 return;
  37
  38         if (printk_ratelimit()) {
  39                 printk(KERN_INFO
  40                         "warning: process `%s' used the deprecated sysctl "
  41                         "system call with ", current->comm);
  42                 for (i = 0; i < nlen; i++)
  43                         printk(KERN_CONT "%d.", name[i]);
  44                 printk(KERN_CONT "\n");
  45         }
  46         return;
  47 }
  48
  49 #define WARN_ONCE_HASH_BITS 8
  50 #define WARN_ONCE_HASH_SIZE (1<<WARN_ONCE_HASH_BITS)
  51
  52 static DECLARE_BITMAP(warn_once_bitmap, WARN_ONCE_HASH_SIZE);
  53
  54 #define FNV32_OFFSET 2166136261U
  55 #define FNV32_PRIME 0x01000193
  56
  57 /*
  58  * Print each legacy sysctl (approximately) only once.
  59  * To avoid making the tables non-const use a external
  60  * hash-table instead.
  61  * Worst case hash collision: 6, but very rarely.
  62  * NOTE! We don't use the SMP-safe bit tests. We simply
  63  * don't care enough.
  64  */
  65 static void warn_on_bintable(const int *name, int nlen)
  66 {
  67         int i;
  68         u32 hash = FNV32_OFFSET;
  69
  70         for (i = 0; i < nlen; i++)
  71                 hash = (hash ^ name[i]) * FNV32_PRIME;
  72         hash %= WARN_ONCE_HASH_SIZE;
  73         if (__test_and_set_bit(hash, warn_once_bitmap))
  74                 return;
  75         deprecated_sysctl_warning(name, nlen);
  76 }
  77
  78 static ssize_t do_sysctl(int __user *args_name, int nlen,
  79         void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
  80 {
  81         int name[CTL_MAXNAME];
  82         int i;
  83
  84         /* Check args->nlen. */
  85         if (nlen < 0 || nlen > CTL_MAXNAME)
  86                 return -ENOTDIR;
  87         /* Read in the sysctl name for simplicity */
  88         for (i = 0; i < nlen; i++)
  89                 if (get_user(name[i], args_name + i))
  90                         return -EFAULT;
  91
  92         warn_on_bintable(name, nlen);
  93
  94         return binary_sysctl(name, nlen, oldval, oldlen, newval, newlen);
  95 }
  96
  97 SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
  98 {
  99         struct __sysctl_args tmp;
 100         size_t oldlen = 0;
 101         ssize_t result;
 102
 103         if (copy_from_user(&tmp, args, sizeof(tmp)))
 104                 return -EFAULT;
 105
 106         if (tmp.oldval && !tmp.oldlenp)
 107                 return -EFAULT;
 108
 109         if (tmp.oldlenp && get_user(oldlen, tmp.oldlenp))
 110                 return -EFAULT;
 111
 112         result = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, oldlen,
 113                            tmp.newval, tmp.newlen);
 114
 115         if (result >= 0) {
 116                 oldlen = result;
 117                 result = 0;
 118         }
 119
 120         if (tmp.oldlenp && put_user(oldlen, tmp.oldlenp))
 121                 return -EFAULT;
 122
 123         return result;
 124 }
 125
 126
 127 #ifdef CONFIG_COMPAT
 128
 129 struct compat_sysctl_args {
 130         compat_uptr_t   name;
 131         int             nlen;
 132         compat_uptr_t   oldval;
 133         compat_uptr_t   oldlenp;
 134         compat_uptr_t   newval;
 135         compat_size_t   newlen;
 136         compat_ulong_t  __unused[4];
 137 };
 138
 139 COMPAT_SYSCALL_DEFINE1(sysctl, struct compat_sysctl_args __user *, args)
 140 {
 141         struct compat_sysctl_args tmp;
 142         compat_size_t __user *compat_oldlenp;
 143         size_t oldlen = 0;
 144         ssize_t result;
 145
 146         if (copy_from_user(&tmp, args, sizeof(tmp)))
 147                 return -EFAULT;
 148
 149         if (tmp.oldval && !tmp.oldlenp)
 150                 return -EFAULT;
 151
 152         compat_oldlenp = compat_ptr(tmp.oldlenp);
 153         if (compat_oldlenp && get_user(oldlen, compat_oldlenp))
 154                 return -EFAULT;
 155
 156         result = do_sysctl(compat_ptr(tmp.name), tmp.nlen,
 157                            compat_ptr(tmp.oldval), oldlen,
 158                            compat_ptr(tmp.newval), tmp.newlen);
 159
 160         if (result >= 0) {
 161                 oldlen = result;
 162                 result = 0;
 163         }
 164
 165         if (compat_oldlenp && put_user(oldlen, compat_oldlenp))
 166                 return -EFAULT;
 167
 168         return result;
 169 }
 170
 171 #endif /* CONFIG_COMPAT */